Defect assessment methodology of plastic encapsulated devices based on scanning acoustic microscope inspection

Scanning acoustic microscope (SAM) inspection is becoming an essential nondestructive procedure to defect delamination, voids, cracks in the plastic encapsulated devices. The C-scan SAM (C-SAM) is the most widely used mode since it can provide a planar defect view efficiently at specific depth level. However, the accuracy of the inspection largely depends on the operator's experience and may lead to opposite conclusions about the inspection results. This study focuses on two typical failure cases using C-SAM inspection, the justification of accuracy and defect verification were studied by microsectioning via optical microscope (OM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). This work provides guidance for the reliability of plastic encapsulation based on scanning acoustic microscope inspection.